Grab.



D. .I. BARNARD.

GRAB.

APPLICATION FILED MAY 4, 1912.

1,205,425. Patented Nov. 21, 1916.

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D. J. BARNARD.

GRAB.

APPLICATION FILED MAY 4, I9I2.

Patented Nov. 21, 1916.

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D. J. BARNARD.

G RAB. APPLICATION FILED MAY 4,1912.

1,205,425. Patnted Nov. 21, 1916.

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DUDLEY JaMEs BARNARD, 01 EAST HAM, ENGLAND.

GRAB.

Specification of Letters Patent.

Patented Nov. 1916.

Application filed May 4, 1912. Serial No. 695,069.

To all whom it may concern:

Be it known that I, DUDLEY JAMES BAR- NARD, a subject of the King ofGreat Britain and Ireland, residing at East Ham, England, have inventeda new and useful Improvement in Grabs, of which the following is aspecification.

This invention relates to grabs of what is known as the single chaintype, that is to say, in which the hoisting chain or rope is employedfor also closing and opening the bucket. In such grabs of this type asconcern the present invention the hoisting chain or rope is wound upon awheel or drum which is automatically locked and unlocked at the propertimes and cooperates with or controls the bucket closing andtipping'de-- vice. V

The main object of the present invention is to provide means forincreasing the. mun

ber of windings of the hoisting chain on the drum thus enabling thedigging action to take place through a greater number of revolutions ofthe winding mechanism than heretofore, without increasing the length ofthe closing chains, a greater ratio between the hoisting and closingchains being thus obtained thereby giving the grab greater facility inworking upon dense substances such as iron ore; further objects of theinvention are to provide an improved tipping device; to insure thebucket closing chains both working and sharing the working strainequally; and to provide the bucket.

sections with a suitable buffer.

According to the invention the ratio between the winding capacity of thehoisting drums and the drums upon which the bucket closing chains arewound is increased thereby causing the winding drum to make .anincreased number of revolutions, for

which purpose means are provided for preventing or delaying the lockingtogether of the co-actmg parts of said winding device while the grab isdischarging or tipping its contents. The other improvements will be setout hereinafter.

The invention will'now be described more fully with reference to theexamples thereof illustrated in the accompanying drawings,

in which Figure 1, is a side elevation, partly in section, of oneexample of grab constructed in accordance with this'invention showingthe position of the parts after tipping, but prior to the hoisting chainbeing slackened. Fig. 2 is a side elevation thereof with the bucketsections closed and when hoisted with its load to the elevation to whichit is to be raised prior to tipping. Fig. 3 is a side elevation, partlyin section, illustrating the drum locking means and part of the tippingmeans in the positions which these parts occupy after the hoisting chainhas been slackened, and after the drum, acting under the influence of aspring, has wound said hoist ing chain on its periphery. Fig. 4 is asimilar view of the same parts in the positions they occupy when thegrab is in the condition shown in Fig. 2,that is, prior to being tipped.Fig' 5 illustrates the relative positions of the fast and loose camswhen the grab has been landed on the material to be picked up but priorto the hoisting chain being slackened. Fig. 6 'is an elevation, partlyin section, of. a detail showing the lower stop on the hoisting chain.

I In the drawings, the bucket sections at a are shown pivoted togetherat a by means of brackets a a furnished at both ends of the bucket. Saidsections a are pivoted at a to the lower ends of arms 6 b and the lefthand bucket section is pivoted at a to a box or casing c, looselymounted on a shaft 6, which casing partly incloses a drum (Z alsoloosely mounted on the shaft 6. right hand bucket section is pivotallyconnected at the point a to a link 5 the upper end of which is looselymounted on the shaft pivoted together at their upper ends to a pivot pinZ2 carried by a bridge piece which allows them to spread or approacheach other according to the movements of the bucket sections.

The links 5 transmit the up and down" movements of the drum rl to theright hand bucket section to which they are connected and thereby alsoassist the opening and clos- The ing of the grab, thecasingc yielding tothis I action by tilting about the pivots a This tilting of casing 0serves to bring'a tipping lever 7' into position forengaging a tipping.

device Z as hereinafter described.

lVithin thedrum (Z a coiled spring cl is arranged, the outer end ofwhich, as shown at Fig. l, is secured to the drum while the inner end issecured to some non-rotatable part which is fast with, say the links Z)or with the casing c. The drum (Z, is provided at one end with a gravitycatch or slide (Z adapted to cooperate with a cam 0 fixed to the shaft6, and a cam h, loosely mounted on said shaft, as hereinafter moreparticularly described.

The bucket sections a a are closed by means of chains 9 the ends ofwhich are connected to spools e fixed to the spindle e, the chains beingsuspended from the bridge piece 5 For the purpose of limiting theunwinding action of the drum (Z, a stop '5 is fixed upon one of thelinks of a hauling chain the position of such stop on the chain beingsuch that it comes into contact with the bridge piece when the chain fhas been hauled up to completely close the buckets, after which the grabis hoisted the parts being arranged as shown in Fig. 2.

The mechanism will now best be further described by referring to itsoperation.

Figs. 1, 5 and 6, represent the relation of the parts when the emptygrab has just landed onto the material, with its jaws fully opened, andprior to the hoisting chain being slackened, the stop 2' on the chain asshown in Fig. 6, bearing against the bridge piece, with one or moreconvolutions of the hauling chain still on the drum, and the cams onshaft 0 occupying the position shown in Fig. 5. f, with the parts in thepositions above indicated the hoisting chain 7'' is relaxed the drumunder the influence of its spring revolves, in this-instance in acounter-clockwise direction as indicated by the arrow to, Fig. 1,carrying with it the sliding catch (Z which at the commencement of suchmovement is hearing on the cam h and falls away therefrom as the drumturns, said cam it, by reason of the fact that the heaviest part of thecam is to the right of the center, being held by gravity in the positionshown in Fig. 5, in which its radial face abuts against the radial faceof the fixed cam 6 until the catch (Z again approaches approximately toa vertical position above the shaft 6. The loose cam h as shown issomewhat higher in contour at its highest point than the fixed cam e andtherefore the catch (Z in its travel around the shaft 6, after it hasdropped toward the faces of the cams when approaching its up pervertical position will strike the project ing part of the cam 7L andknock it away so that said cam will then fall into its lowermostposition, as shown in Fig. 3. By this movement of rotation, under theaction of its spring (Z, the drum (Z will wind on to its periphery alength of the hoisting chain 7', the length of chain wound on the drumbeing determined by the provision of means for limiting the rotation ofthe drum in this particular direction even as the stop 71 limits themovement in. the reverse direction. The means employed may for examplebe either of the means illustrated in the drawings o British patentspecification No. 9132 of 1908. To close the bucket sections and hoistthe grab the hoisting chain f is pulled by the 'rane and is therebyunwound from the drum (Z until the stop 2' comes into engagement withthe bridge 6 said drum being thereby rotated, in this instance, in aclockwise direction in opposition to its spring. Considering the closingaction particularly, the parts being in the position shown in Fi 3 thesliding catch (Z is at the commencement of such rotation of the drumbrought up against the radial face of the fixed earn 6 so that thespools 6 will turn with the drum and wind up the bucket closing chains5, thereby raising the shaft c'and with it the parts carried therebytoward the bridge piece L. When the stop i comes into engagement withthe bridge 6 the jawsof the grab have been closed as just described, andthe bucket closing members occupy the position indicated in Fig. 4. Thecontinued hauling upward of the chain will elevate the entire gra b.lVhen the grab has reached the top of its ascent a trip pawl j pivotedto the upper end of the tipping lever comes into engagement with andpasses the flange Z of the tipping device Z. When the grab has beenplaced above -the position where it is desired to deposit the contentsof the bucket the chain is lowered, and, when the part 7' engages withthe flange Z the bell crank lever j is turned about its pivot The outeror free end of the bell crank lever 7' has an are shaped part j which,normally, is more or less concentric with the shaft 6, but which whenthe lever is tripped will press against the inner face of. an outwardlyprojecting lug or flange (Z at the head of the sliding catch d. Thispulls said catch out of engagement with the cam e and thus releases thedrum (Z from the shaft 6 and allows said drum and the other parts of themechanism to fall by their own weight and tip the buckets a a, thechains g being thereby unwound from the spools c a part of the haulingchain below the stop 2' being also unwound from the drum. 1

This movement is permitted by reason of the fact that the part of thehauling chain 7 which is below the bridge 5 is relieved by the stop a ofthe weight of the grab.

It is during this last described movement that the loose snail cam itcomes into operation, and in order to fully appreciate its use themovements of the several parts will be more particularly described.

As soon as the catch d has been pulled li t out of engagement with thefixed cam 6 the parts will, as above stated, fall by their own weight,the drum, being free from the shaft 0 and that part of the hauling chain7 between the stop 71 and the crane hoisting the reverse direction tothat of the hauling chain on the drum together with the weight of thegrab'acting through the shaft 6 cause the shaft 6 andthereby the spoolsto rotate in a counter-clockwise direction. These opposite rotarytendencies of the drum (Z and spools c. were resisted so long as thedrum (Z and shaft 6 were held together by the engagement of the catch dwith the cam 6 During the rotation of the shaft 6 the cam 6 willovertake the loose cam h and the catch (Z will travel idly over theperipheral faces of these cams so that a very considerable amount ofrelative rotation takes place between the drum (Z and the shaft 6,amountingto as many revolutions as are required by the length of thebucket closing chains 9. W hen this movement is completed the cams e andit will again occupy the relative positions shown in Fig. 5, the innerend of the catch (Z bearing on the face of the cam It. But for theprovision of the loose cam h the drum (Z and shaft 6 would, after therelease of the catch (Z be able to make only a short relative rotarymovement because the catch (Z which is a gravity catch, would onreaching its upper position, fall down on to the shaft 6 and would thusvery soon lock against the radial face of cam e and prevent the chains 9being unwound to the full extent and the jaws from opening to the fullextent. The provision of the loose cam it however, prevents this andtherefore allows of a complete unwinding of the bucket closing chains 9,and, consequently, at the next operation, (after the hoisting chain hasbeen slackenech) of a considerably longer bucket closing movement,thereby giving a greater length of time for the bucket sections to acton the material being lifted.

The tipping lever j between the trip pawl and the bell crank lever orthe like y' is rigid and is loosely jointed to said bell crank lever soas to be able to fall laterally one way or the other such lateral motionbeing limited by stops j j in a bracket y' which serves to guide the rodj. The lever 3' is pivoted at 7' to the casing c, and as previouslystated, has an arc-shaped part which partially surrounds and is normallyconcentric with the shaft 6, and which is normally located between saidshaft and the concentric circular path of travel of the lug (Z on thecatch 6Z2. Normally, that is to say when not in use, said tipping leverfalls laterally out of the way, although restricted in its lateralmovements by the stops j and in this position,'as already stated, thearc shaped part of the le ver j lies inwardly of the lug (Z on the catch(Z so that said catch can travel around without being tripped by thesaid are shaped part; when, however, the buckets close together asaforesaid the tilting of the drum box or casing 0 about its hinge pins awill cause the trip pawl j carried by the tipping lever to be broughtinto position for engaging flange Z of the tipping device Z. On-theascent of the grab the trip pawl j strikes the bottom flange Z of thetipping ring Z and yields thereto or tilts so that it can pass saidflange, and once past the same it falls back into normal position asshown in Fig. 2. On the descent of the grab, said pawl engages the upperside of said lug but is unable to yield thereto, with the result thatthe rod j is pulled upwardly and the lever j is tilted so as to move itsarc-shaped part outwardly into engagement with the lug (Z on the catch6Z2 and thereby move said catch out of engagement with the abrupt faceof the fast cam c and so release the shaft 0 and the spools c thereonfrom the spring drum (Z and permit these spools to fall into the bucketopening position shown in Fig. 1, the drum (Z revolving in a clock wisedirection and the shaft 0 and spools c in an anti-clockwise direction.The members j y" are arranged to remain at all times within the outsidediameter of the bucket so that projecting parts in this portion of thetipping device are avoided. The closing chains are attached to thespools e at points in line with the tip of the fast cam c and thereforewhen the hoisting chain is slackened, the impact of the catch (Z againstthe tip of the cam it will occur while the abutting cam faces arevertically above the center of the shaft or are slightly short of thisposition, approximately as shown in Fig. 5. The cam it therefore, beingloose, will fall away partly from said impact and partly by gravity,until it hangs in a position approximately vertically below the centerof the shaft. The catch (Z will, when it has passed the tip of the fastcam 6 fall into the space openedup between the two opposing faces, butwhen in the course of the drums revolution it has passed the horizontalposition it will fall radially outward, under the influence of gravity,along its lateral guides. These guides allow the catch d a suflicientlength of outward move ment to permit its inner end to clearthe tip oftheloose cam 71, when passing around the under side of the shaft 6, sothat the drum (Z can revolve, and in revolving of course carry the catch(Z idly around the cams e and it, the drums revolving in ananti-clockwise direction until the predetermined length of hoistingchain has been wound on the drum and until the parts again occupy theposition indicated in Fig. 8.

In order to obviate a strain not properly divided between the twobucketclosing chains the latter are dispensed with and a single chain isemployed: such chain has hereinbefore been referred to as chains, butthat expression was used as referring to the two portions of the singlechain which are wound on to the two spools 6. Instead of being fixed tothe frame above the bucket, as was thecase with the two chains formerlyemployecL-or of running freely over two sheaves at the top of the grabto wind from a drum on one side to a drum on the other side as has beenproposed in connection with a difierent type of apparatus,the singlechain 9 may be supported in any way, in this instance by means of eyes9, 9, that will permit it to adjust itself toward one side or the other,and thus prevent a onesided strain coming upon it. This adjustment wouldusually be Very small in amount, but suflicient for its purpose. Suchsupporting device would be so arranged as to leave a clear way for thehoisting chain or ro e.

The brackets (0 a or the top beams or shoulders, of the bucket sectionsmay be provided with means, in the example illus trated, a buffer is, toprevent their mutual shock when opened suddenly.

It will be obvious that, in place of the hoisting chain 7 or the chains9 of the bucket members, rope might in either case be used if preferred,and accordingly in the following claims the word chain is to beunderstood as including either a. chain or a rope.

To assist in furnishing a clear understanding of the operation of theimproved grab, the present drawings illustrate and the foregoingdescription refers to a number of features not specifically claimed as apart of the present invention, the same being substantially those shownand described in British Patent 9132 of April 27th 1908, issued tomyself and James MacDonald.

What I claim is 1. In a grab, the combination with hinged complementarybucket members of a drum or wheel, a hoisting chain adapted to be woundthereon, a shaft upon which such drum is freely mounted, bucket closingmeans normally disconnected from said drum carried by said shaft andmeans for operatively connecting said bucket closing means with saiddrum, comprising a sliding locking catch carried by the drum, a fast camcarried by and rotating with said shaft positioned to co-act with saidlocking catch, and a loose cam positioned to co-act with the lockingcatch and shroud said fast cam during a certain period of the revolutionof the drum.

2. In a grab, the combination of a plurality of complementary bucketmembers, a spring drum, an axle therefor, a shield or casing for saiddrum, a pivotal connection between said shield or casing and one of theaforesaid bucket members, and a link pivotally connected to said axleand to the other bucket member.

3. In a grab, the combination of a plurality of complementary bucketmembers, of a drum, a hoisting chain adapted to be wound thereon, bucketclosing means normally disconnected from said drum, means foroperatively connecting said bucket closing means with said drum,comprising a locking catch carried by the drum, a fast cam carried byand rotating with the bucket closing means positioned to co-act with andengage said locking catch and a loose cam positioned to co-act with thelocking catch and shroud the fast cam and trip means for releasing saidlocking catch from the fast cam, one member of said trip means beingcarried by the grab, and another co-acting member thereof beingsupported in the path of travel of said first named trip member, andmeans connected with the aforesaid bucket members for bringing saidfirst named trip member, when said bucket members are closed, into apath of travel where it can come into operative relation to said secondnamed trip member.

at. In a grab, the combination with hinged complementary bucket membersof a drum, a hoisting chain adapted to be wound thereon, bucket closingmeans normally disconnected from said drum, means for operativelyconnecting said bucket closing means with said drum, means comprising asliding locking catch carried by the drum, a fast cam carried by androtating with the bucket closing means positioned to co-act with andengage said locking catch and a loose cam positioned to co-act with thelocking catch and shroud the fast cam during a period of the revolutionof the drum, and means comprising a tipping ring carried separately fromthe grab, and a loose tripping lever carried by the grab engaging withsaid tipping ring,

, for throwing said locking catch out of engagement with the fast cam.

5. In a grab, the combination with hinged complementary bucket membersof a hoisting chain, a shaft supporting said bucket members, a drummounted loose on said shaft actuated by said chain, bucket-closing meansnormally disconnected from said drum, means including a sliding lockingcatch on the drum and a fast cam on the shaft for operatively connectingsaid bucket-closing means with said drum, and means for delaying suchconnection, com- 7 prising a loose cam positioned to co-act with thelockmg catch and shroud sald fast cam during a certain perlod of thedrums revolution and to be pushed away therefrom In witness whereof Ihave hereunto set during an opposite revolution of the drum, my hand inthe presence of two subscribing the bucket-operating parts being soadjust- Witnesses.

ed or proportioned to each other that such DUDLEY JAMES BARNARD. pushingaway will take place when said lVitnesses:

cams are at the upper part of their circular ARCHIBALD ERNEST HARRISON,path. ALEXANDER J OSEPH PLATON.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner of Patents, Washington, 13.70.

